Abstract: A loop antenna apparatus is disclosed which includes a main conductive loop arranged on a first surface, a plurality of supplemental conductive loops connected to the main conductive loop and arranged on different surfaces from the first surface, respectively, a plurality of signal feeding points provided in different loops of the main and supplemental conductive loops, an output terminal and change-over switches for selectively connecting one of the plurality of signal feeding points to the output terminal.

Abstract: An antenna system is disclosed which has a loop antenna divided into n conductive members at n pairs of divisional points where n is a positive integer not smaller than 2, n feeders connected to the n pairs of divisional points respectively, a signal feeding point, and at least one impedance element. In this case, electrical switching circuits are connected between the n feeders and the impedance element, and an electrical control circuit is connected to the electrical switching circuits for selectively connecting the feeding point to one of the n feeders and at the same time for selectively connecting the impedance element to another of the n feeders, so that the directivity characteristic of the antenna system is variable controlled.